Method and apparatus for depositing foundations under submerged structures

ABSTRACT

The disclosure teaches a novel method of depositing foundationproviding sand under structures submerged in water, such as underwater tunnels, as well as apparatus for carrying out the method. In accordance with the teachings, the structure contains an opening extending from the top to the bottom of the structure. An arrangement comprising sand-jetting means and water suction means are extended through the opening from the top such that the jetting and suction means extend beyond the base of the structure. The jetting means is rotatable through 360*. Sand is jetted through the arrangement while water under the structure is simultaneously removed by the suction means whereby a bank of sand is built up under the structure. The jetting means is aimed slightly above the horizontal.

United States tent 1 1 [111 3,782,t27 Olsen [451 Jan. 1, 197A [54] METHOD AND APPARATUS ma 482,246 9/1929 Germany 302/63 DEPOSITING FOUNDATHONS UNDER SUBMERGED STRUCTURES [76] Inventor: Kaare Ritter Olsen, 80 Selkirk Crescent, Hudson, Quebec, Canada [22] Filed: June 12, 1972 [21] Appl. No.: 261,655

[52] U.S. Cl. 611/50, 61/63, 302/16, 302/66 [51] int. Cl E02d 27/52 [58] Field of Search 61/50, 63, 43; 302/63, 58, 53, 14, 15, 16, 66

[56] References Cited UNlTED STATES PATENTS 3,665,718 5/1972 Griffioen et a1. 61/46 2,191,845 2/1940 Bretting r 61/63 3,188,145 6/1965 Strong 302/63 3,577,738 5/1971 Havno 61/50 FOREIGN PATENTS 0R APPLICATIONS 425,092 3/1911 France 61/50 mix-.31:

Primary ExaminerJacob Shapiro Att0rneyA1an Swabey et a1.

[57] ABSTRACT The disclosure teaches a novel method for depositing foundation-providing sand under structures submerged in water, such as underwater tunnels, as well as apparatus for carrying out the method. In accordance with the teachings, the structure contains an opening extending from the top to the bottom of the structure. An arrangement comprising sand-jetting means and water suction means are extended through the opening from the top such that the jetting and suction means extend beyond the base of the structure. The jetting means is rotatable through 360. Sand is jetted through the arrangement while water under the structure is simultaneously removed by the suction means whereby a bank of sand is built up under the structure. The jetting means is aimed slightly above the horizontal.

8 Claims, 19 Drawing Figures LIFT PATENTEUJAH 1 1974 3,782,127

SHEET NF 7 s/m/PE x papa/1c TRANSIT/0N SEC 0ND ELEMENT E PATENTED JAN 1 I974 SHEET t 0? T PATENTEUJAH 1 mm SHEEI S (If 7 1 METHOD AND APPARATUS FOR DEPOSITING FOUNDATIONS UNDER SUBMERGED STRUCTURES BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a method for depositing foundation-providing sand under structures submerged in a body of water, and to apparatus for carrying out the method.

2. Description of the Prior Art In the construction of submerged tunnels by the float-and-sink method, tunnel elements carrying the roadway and service conduits, etc., are lowered into a trench excavated in the bed of the body of water and temporarily supported at a fixed elevation above the bed. A fill, usually of sand, is deposited in the space be tween the bottom of the elements as their permanent foundation. This is done by jetting into the space, under pressure, a mixture of sand and water, while at the same time establishing a suction flow of water from the space in an opposite direction. Apparatus for this purpose has included a system of pipes leading from the gantry travelling on rails above the element, down the side of the element and then underneath it. This has disadvantages. The gantry is heavy and complex and the number of passes that have to be made along each side of the element, to complete the fill from one end to the other, and the need for divers to descend frequently,to place the gantry on its rail and to convert long pipes to short pipes and vice versa several times for the various passes that have to be made, makes this apparatus undesirable. The gantry is also vulnerable to the action of any current and has to be counterbalanced accordingly. The process is also handicapped by the limited access from the sides of the element.

SUMMARY OF THE INVENTION It is an aim of the present invention to overcome these disadvantages and to provide certain positive advantages as will be apparent from the description to follow.

In accordance with the invention, a method for depositing sand foundation providing sand or other material under structures submerged in a body of water wherein the structure consists of two end walls along the length thereof comprises positioning sand or other material depositing means entirely within the confines of said end walls and depositing sand therethrough.

Apparatus for carrying out the method comprises means for depositing sand under said structures and for removing water from under said structure, characterized in that the means is adapted to be positioned entirely within the confines of said end walls.

BRIEF DESCRIPTION OF THE DRAWINGS Having thus generally described the invention, it will now be referred to more specifically by reference to the accompanying drawings which illustrate preferred embodiments, and in which:

FIG. 1 is a plan view of a partially built submerged tunnel according to the invention;

FIG. 2 is a fragmentary perspective view on a larger scale of part of the partially built tunnel of FIG. 1, before the foundation is jetted into place;

FIG. 3 is a fragmentary diagrammatic plan view illustrating the way in which the foundation is progressively built up by jetting sand under the tunnel elements;

FIG. 41 is a fragmentary diagrammatic side elevation;

FIG. 5 is an enlarged vertical cross-section through a tunnel element and foundation as on a still larger scale showing the relationship of the foundation sand to the element;

FIG. 6 is a vertical cross-section as in FIG. 5 but with concrete ballast in place within the shell of the element;

FIG. 7 is a greatly enlarged fragmentary vertical cross-section through a tunnel element showing a portable sand jetting unit in place in one of the openings in the element;

FIG. 8 is a horizontal cross-section (looking up) along the line 8-8 of FIG. 7 on a further enlarged scale;

FIG. 9 is a side elevation of the jetting end of the jetting unit shown partly in section;

FIG. 10 is a front elevation, partly in section, of the jetting end of the jetting unit on the same scale as FIG.

FIG. 11 is a horizontal cross-section (looking up) along the line 11-11 of FIG. 9 on a further enlarged scale;

FIG. 12 is a horizontal cross-section (looking down) along the line 12-12 of FIG. 7 on a further enlarged scale;

FIG. 13 is an isometric, partially fragmented, view of the end of the jetting unit to illustrate a feature thereof;

FIG. 14 is a horizontal cross-section on the line 14-44 of FIG. 15 showing the construction of the pumps;

FIG. 15 is a horizontal cross-section along the line 15-15 of. FIG. 14 and shows further details of the pump construction;

FIG. 16 is a side elevation of the rotating mechanism;

FIG. 17 is a top plan view of the rotating mechanism;

FIG. 18 is a partially fragmented top plan view of the submerged tunnel to illustrate in greater detail the hole through which the jetting mechanism is lowered as well as a keying arrangement therein; and

FIG. 19 is a partially fragmented side elevation of the hole in FIG. 18 showing further details of the keying mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the top of a partially built submerged tunnel made up of a ventilation tower A communicating with an open cut approach B. C is a transition section, connecting the tower A with a first tunnel element D which, in turn, has been submerged into place and connected to a second tunnel element E. For purposes of the following description, it is assumed that the elements A, B and C are built on dry land L. Elements D and E were floated into place and connected under water. The element D has already been placed and a permanent foundation laid under it' The element E is connected to the element D, but its foundation still has to be laid.

As shown in FIG. 2, the element E is held at a level by jacks 15 and 17 at the outer end and supported on inboard horns l9 and 21, resting and connected to the element D. A space M is left underneath the element E for placing its foundation.

Each tunnel element D, E is constructed of an elongated steel shell 23 encasing a body 25 of enough ballast concrete to cause it to sink. Within the body are reinforced concrete tubes 27, 29 to accommodate roadways, ventilation ducts and service conduits. Transversely extending spaced-apart steel bulkheads 31 protruding from the shell 23 at each side strengthen the element and divide it into a series of sections 33 between the bulkheads 31.

There are a number of vertical cylindrical pipes 35 spaced at intervals along the center of the element and extending from the base or bottom surface to the top of the element. Steel straps 37 extend from bulkhead to bulkhead adjacent each pipe 35, as shown also in FIG. 18. Each pipe 35 constitutes a housing for a portable sand jetting unit as will be described.

A typical unit R, as shown in FIGS. 7 through 13, is made up of a number of parallel pipes 49, 51, 53, 55

I and 57, held in a frame made up of spaced-apart supporting plates 45 welded to longitudinally-extending angle irons 44 and surrounded near the bottom end by a protective casing 41. There is a sand pipe 49, suction pipes 51 and 53, and air supply pipes 55 and 57 which supply air to an airlift pump P.

The unit R is provided with a jetting head (see FIGS.

9, and 13) which is constructed as follows. The pipe 49 has connected to its lower end, by a coupling 62, a

nozzle section 61. The lower ends of the pipes 51 and 53 have connected to their lower ends suction heads 63 and 65, by couplings 64 and 66 respectively. A protective nose casing 68 surrounds the nozzle section 61 and suction heads 63 and 65, except for jetting and suction openings where the ends of the nozzle section 61 and suction heads 63 and 65 engage.

It will, of course, be clear that the entire jetting unit must have a circumference which is less than the circumference of the pipe 35. It will also be obvious that the pipe 35 need not be round, but can be square or oblong or of irregular shape as to best accommodate the portable jetting unit.

In addition, in accordance with the illustrated embodiment, only one row of pipes 35 is shown along the length of the element. However, if the element is exceptionally wide, it is possible that more than one row of pipes will be required in order to fill the complete width under the element, that is, at any point in the width of the element two or more pipes may be required, and such an arrangement is also considered to be within the scope of the invention.

The end of the nozzle 61 is elevated at some angle a from the ground, as shown in FIG. 13. This is to permit the jet to throw the sand some distance from the end of the jet. Without the tilt at the end of the nozzle, sand thrown by the jet would tend to build up directly in front of the nozzle.

Referring to FIGS. 14 and 15, the air pump P is made up of a casing 101 whose lower wall is connected to a pipe 103 which in turn is connected to the nozzle section. Pipe 105, extending from the top of the casing 101, is connected to the suction pipe 53. An air pipe 107 leading from the pipe 57 enters the top of the easing 101. In operation, air is introduced through the pipe 107 to form a stream which strikes a perforated baffle 109 which subdivides it so that it becomes entrained in bubbles in the water coming up through the pipe 103 from nozzle 65 reducing the density of the water and 4 causing it to rise rapidly through the pipe 53. This provides thenecessary suction.

As can be seen in FIG. 11, a similar pump arrangement is provided for nozzle 63 and pipes 51 and 55. The pumps are held in place on plate 301 by bolts 300, as shown in FIG. 12.

The pipes are held in relative position by the plates 45. A bottom view of one such plate is shown in FIG. 8. The plate is free to rotate within the frame structure formed by the angle irons 44.

Above the frames, the pipes 49, 51, 53, 55 and 57 are connected to a rotating mechanism K and beyond to upper ends connected to elbows 302 and 303 above a bracket W connected to a work platform located above the surface of the water.

The elbow 302 leads to a flexible pipe connection from conventional sand mixing and pumping equipment (not shown). Pressures are developed at the pump to carry this mix of sand through the pipe 49 and to project it from the nozzle 61 with the necessary velocity. The top end of pipe 53 is provided with an elbow 303 leading to outlets 304 and 305. The outlet 305 feeds a sampling tank close to the controls where an examination of the discharge can be used to judge whether the void under the element is filled or not. If no sand is being discharged at outlet 303, then the void is not full and filling operation is being continued. If a substantial amount of sand is being discharged from outlet 303, then the void is filled.

All elbows which are subject to the action of sand are lined with rubber in order to make them wear resistant.

FIGS. 16 through 19 illustrate in some detail the rotating mechanism K. It includes a hydraulic motor 201 remotely controlled through pressure hoses 223 from a control unit from the operating barge at the surface actuating a chain drive 203 engaging a toothed ring 205 mounted on a drum 202.

The drum 202 carries a lower collar 207 which engages idler rollers 209 on a support frame 211. The lower rim of the drum 202 rests on idler rollers 213 mounted on the frame 211. The frame 211 has feet or lugs 215 which engage in recesses 217 in the top of the element E. Idler rollers 229 engage an upper collar 221 on the drum 202.

The jetting unit R is rotated by rotation of the drum 202 by the hydraulic motor 201. The drum 202 can be rotated 360 in either direction.

The rotation of mechanism K is controlled from a remote hydraulic control panel located on a barge. The sand jet and airlift operation is also controlled by valves located on the barge.

In operation, the unit R is inserted into an opening 35 in the element E. It may be guided into place by a diver, with a crane performing the actual lowering operation. When the lower end of the apparatus R is guided into the opening 35 and rotation is started by the rotating mechanism K, the unit R will drop into the opening, and its lugs 215 will engage in the recesses at the top of the unit. so as to prevent the unit K from turning relative to the element E. Once the unit R is locked into place, sand jetting can start.

The jetting operation is as follows. First, a rock berm M is established by depositing stone and rock at the outer end of the tunnel section as shown in FIGS. 3 and 4.

Thejetting unit R is inserted into a first vertical opening 35. The nozzle 61 is first aimed along the center line towards the berm and jetting is continued until the indicator shows that the cavity is filled in that direction. This is indicated when the discharge of water from the air pump contains a certain amount of sand. The nozzle is then turned 60, say to port, and the jetting procedure started up again, until the indicator shows that the fill is complete in that direction. Then the nozzle would be rotated 120, this time to starboard, and jetting continued until the indicator shows that the fill in that direction completed. This would give a fill pattern substantially as shown in FIG. 3. Variations of this procedure are, of course, possible.

Then, the jet apparatus R would be moved in the inshore direction to the next succeeding opening 35 and the process repeated. The pattern can be varied in that the jetting apparatus can be turned 360 and thus aimed in any given horizontal direction so as to deal with conditions arising from obstructions or irregularities in the bed.

The size of the pipes 49, 511 and 53 may vary. A typical installation would have a pipe 49 of an inside diameter of inches and pipes 51 and 53 with inside diameters of=8 inches.

As can be seen in FIG. 6, the pipe 35 can be filled with ballast concrete after all the sand has been deposited. The cavity which remains in the place of the jetting nozzle, shown in FIG. 5, can be filled by jetting from the next pipe. In the case of the last pipe, or any other pipe, the cavity can be filled by concrete supplied through the pipe 35 under pressure. The concrete will be forced out of the bottom of the pipe and will compact the sand around it and eventually solidify.

The means for supplying air and water to the jetting arrangement are well known to one skilled in the art and require no further elaboration here.

The description of the tunnel construction is a specific example. The actual jetting operation may be used for placing foundations under other structures, for example, under water, oil or other storage, or for any other structure.

Although an embodiment of the invention has been described above, this was for the purpose of illustrating, but not limiting, the invention. Various modifications which will come readily to the mind of one skilled in the art are considered to be within the scope of the invention as defined in the appended claims.

I claim:

I. A method of forming a sand foundation under water between a bed and the base of a submerged structure;

said submerged structure comprising side walls and a top and bottom surface and an opening between said side walls extending from said top to said bottom surface;

said method comprising directing a mixture of sand and water beneath said structure in a restricted jet in a substantially horizontal direction and, at the same time, establishing a suction fiow close to the jet in a substantially opposite horizontal direction; characterized in that means for providing said jet is inserted in said opening from the top of said structure and through said structure and past the base of said structure;

said means thereby being located inboard of said structure and directed outboard thereof;

whereby a bank of sand is built progressively between the bed and the base of the structure in the inboard direction towards the jet.

2. A method, as defined in claim 1, in which the structure is elongated and a first bank of sand is initially built from a jet located inboard of the structure within jetting range of the structures end and inboard of its sides, and subsequent banks are formed in continuation of the first bank from jets located further inboard of the structure at progressive locations under the length of the structure thereby to complete a sand foundation for supporting the structure on the bed.

3. A method, as defined in claim 1, in which the jet is directed in a direction slightly upwards from the horizontal towards the base of the structure whereby the latter serves as a boundary of the jet to promote laminar flow.

4. A method, as defined in claim 2, in which the jet is directed in a direction slightly upwards from the horizontal towards the base of the structure whereby the latter serves as a boundary of the jet to promote laminar flow.

5. A portable jetting assembly comprising:

retaining frame means insertable into a submerged structure;

a plurality of pipes connected together by and within the retaining frame means and adapted in use to extend from above water level to a jetting site beneath the water, one of said pipes being adapted to carry a mixture of sand and water under pressure, at least one other pipe adapted to carry air and water so as to remove water from the site of jetting by suction;

a mounting frame mountable on said submerged structure;

a motor carried by said mounting frame and having a drive connection to the retaining frame whereby it is adapted to rotate the pipe assembly relative to the mounting frame;

said plurality of pipes extending to connections above said water level;

a nozzle member on the submersible end of said one pipe having a jet tip part with a jetting opening aimed substantially laterally of the direction of said one pipe, and an end piece on the other pipe having a suction tip part having an opening facing in substantially the same direction as the nozzle tip part opening;

characterized in that both tip parts are of short enough length to lie within the extension of a circle subscribed about a cross-section through the frame and the pipes.

6. A jetting assembly, as defined in claim 5, in which a housing surrounds the end pieces, said housing comprising openings about the openings of the tip parts.

7. A jetting,assembly as defined in claim 5, wherein said jet tip part is aimed in a direction slightly upward of the lateral direction of said one pipe.

8. A sand jetting arrangement comprising:

a submerged structure having a body including an upper surface and a base surface adapted to be supported by a sand foundation on a bed;

said structure comprising side and end walls;

at least one opening extending through the body from the upper surface to the base surface and inboard of the side and end walls;

structure for changing the direction of said jetting and suction means whereby a jet may be directed in variable outboard directions to build up a bank of sand from outboard to inboard. 

1. A method of forming a sand foundation under water between a bed and the base of a submerged structure; said submerged structure comprising side walls and a top and bottom surface and an opening between said side walls extending from said top to said bottom surface; said method comprising directing a mixture of sand and water beneath said structure in a restricted jet in a substantially horizontal direction and, at the same time, establishing a suction flow close to the jet in a substantially opposite horizontal direction; characterized in that means for providing said jet is inserted in said opening from the top of said structure and through said structure and past the base of said structure; said means thereby being located inboard of said structure and directed outboard thereof; whereby a bank of sand is built progressively between the bed and the base of the structure in the inboard direction towards the jet.
 2. A method, as defined in claim 1, in which the structure is elongated and a first bank of sand is initially built from a jet located inboard of the structure within jetting range of the structure''s end and inboard of its sides, and subsequent banks are formed in continuation of the first bank from jets located further inboard of the structure at progressive locations under the length of the structure thereby to complete a sand foundation for supporting the structure on the bed.
 3. A method, as defined in claim 1, in which the jet is directed in a direction slightly upwards from the horizontal towards the base of the structure whereby the latter serves as a boundary of the jet to promote laminar flow.
 4. A method, as defined in claim 2, in which the jet is directed in a direction slightly upwards from the horizontal towards the base of the structure whereby the latter serves as a boundary of the jet to promote laminar flow.
 5. A portable jetting assembly comprising: retaining frame means insertable into a submerged structure; a plurality of pipes connected together by and within the retaining frame means and adapted in use to extend from above water level to a jetting site beneath the water, one of said pipes being adapted to carry a mixture of sand and water under pressure, at least one other pipe adapted to carry air and water so as to remove water from the site of jetting by suction; a mounting frame mountable on said submerged structure; a motor carried by said mounting frame and having a drive connection to the retaining frame whereby it is adapted to rotate the pipe assembly relative to the mounting frame; said plurality of pipes extending to connections above said water level; a nozzle member on the submersible end of said one pipe having a jet tip part with a jetting opening aimed substantially laterally of the direction of said one pipe, and an end piece on the other pipe having a suction tip part having an opening facing in substantially the same direction as the nozzle tip part opening; characterized in that both tip parts are of short enough length to lie within the extension of a circle subscribed about a cross-section through the frame and the pipes.
 6. A jetting assembly, as defined in claim 5, in which a housing surrounds the end pieces, said housing comprising oPenings about the openings of the tip parts.
 7. A jetting assembly as defined in claim 5, wherein said jet tip part is aimed in a direction slightly upward of the lateral direction of said one pipe.
 8. A sand jetting arrangement comprising: a submerged structure having a body including an upper surface and a base surface adapted to be supported by a sand foundation on a bed; said structure comprising side and end walls; at least one opening extending through the body from the upper surface to the base surface and inboard of the side and end walls; sand jetting means extending through said opening and having jetting and suction means extending beyond the base surface; and service connections above the upper surface; means above the upper surface connected to said structure for changing the direction of said jetting and suction means whereby a jet may be directed in variable outboard directions to build up a bank of sand from outboard to inboard. 